Heat shield for sealing a flow channel of a turbine engine

ABSTRACT

A heat shield arrangement for local separation of a flow channel within a turbine engine, with respect to a stator housing radially surrounding the flow channel is provided. The heat shield includes two axially opposite joining contours which are each engageable with two components which are axially adjacent along the flow channel. Each provides a complementary reception contour for the joining contours. At least one of the reception contours has an axial clearance, in which the associated joining contour is axially displaceably mounted. At least one seal is provided between the axially displaceable joining contour and the reception contour. The seal is mounted movably within the reception contour or the joining contour in such a way that the seal is deflectable against a surface region of the reception contour or of the joining contour.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation of International Application No.PCT/EP2006/060903, filed Mar. 21, 2006, which is incorporated byreference as if fully set forth.

FIELD OF INVENTION

The invention relates to a heat shield for the local separation of aflow channel within a turbine engine, in particular a gas turbine plant,with respect to a stator housing radially surrounding the flow channel,with two axially opposite joining contours which each can be broughtinto engagement with two components which are axially adjacent along theflow channel and which each provide a complementary reception contourfor the joining contours, of which reception contours at least onereception contour has an axial clearance, along which the joiningcontour joined in it is mounted axially displaceably, at least one sealbeing provided between the axially displaceable joining contour and thereception contour.

BACKGROUND

Heat shields of the generic type designated above are part ofaxial-throughflow turbine engines, through which gaseous working mediaflow for compression or controlled expansion and, because of their highprocess temperatures, those plant components which are acted upondirectly by the hot working media are subject to high thermal loads.Particularly in the turbine stages of gas turbine plants, the rotatingblades and guide vanes, arranged axially one behind the other inrotating blade and guide vane rows, are acted upon directly by the hotcombustion gases occurring in the combustion chamber. In order toprevent the situation where the hot gases flowing through the flowchannel subject to thermal load those regions within the turbine enginewhich are provided in stator regions facing away from the flow channel,heat shields, as they are known, which are provided on the stator sidein each case between two guide vane rows arranged axially adjacently toone another, ensure as gastight a bridge-like sealing as possiblebetween two guide vane rows arranged axially adjacently. Correspondinglydesigned heat shields may also be provided along the rotor unit, whichare in each case mounted on the rotor side between two axially adjacentrotating blade rows, in order to protect corotating rotor componentsfrom the introduction of an excessive amount of heat.

Although the following statements refer solely to heat shields which arearranged between two guide vane rows and to that extent can separate andcorrespondingly protect the stator-side housing and the componentsconnected to it with respect to the heat-loaded flow channel, it is alsoconceivable to provide the following measures on a heat shield whichserves for protecting corotating rotor components and which can beintroduced between two rotating blade rows arranged axially adjacentlyto one another.

FIG. 2 a illustrates a diagrammatic longitudinal section through a gasturbine stage, into the flow channel of which project radially fromoutside guide vanes 1 connected to a stator housing S, the specialconfiguration of which has no further significance in what follows.

A rotating blade 2, connected to a rotor unit, not illustrated, projectsbetween two guide vanes 1 arranged adjacently in guide vane rows and isspaced apart radially on the end face with respect to a heat shield 3which with the guide vane 2 encloses as small a free intermediate gap 4as possible, in order as far as possible to avoid leakage losses of flowfractions of the hot gas stream through the intermediate gap 4. For thispurpose, the rotating blade tip has sealing structures 5 which arearranged so as to rotate freely with respect to what are known asabrasion elements 6.

In order to avoid the situation where hot combustion gases in the regionof the heat shield 3, which in a bridge-like manner spans the interspacebetween two guide vanes 1, 1′ arranged axially adjacently to oneanother, may penetrate into that region of the heat shield 3 which facesradially away from the flow channel, the heat shield 3 provides twoaxially opposite joining contours 7, 8 which extend axially intocorresponding reception contours 9, 10 within the guide vane roots.

The reception contour 9 corresponds to a groove-shaped recess which isdesigned to be complementary with an exact fit to the joining contour 7and which is incorporated in the root region of the guide vane 1. Theaxially opposite joining contour 8 of the heat shield 3 is likewiseinserted into a reception contour 10 which is designed to becorrespondingly complementary to the outer contour of the joiningcontour 8 and which is introduced in the root region of the guide vane1′. However, the reception contour 10 has an axial clearance 11, so thatthe joining contour 8 is mounted axially slideably in the event of acorresponding operationally induced thermal expansion of the heat shield3.

For the fluidtight sealing of the heat shield 3 with respect to therespective reception contours 9, 10 in the root regions of the guidevanes 1, 1′, seals 12, 13 are provided between the joining contours 7, 8and the associated reception contours 9, 10. The seals 12, 13 arelocated each in a groove-shaped recess 14 within the joining contours 7,8 (see also the illustration of a detail according to FIG. 2 b of thejoining region between the joining contour 8 and the reception contour10). The seals 12, 13 are preferably manufactured from an elasticsealing material in the form of a round bar, project partially beyondthe radially outer boundary surface 16 and fit flush, at least along ajoining line, against the surface region 17 of the reception contour 10.

As a result of the sealing action of the seals 12, 13, it is possible,on the one hand, to avoid the situation where hot gases from the flowchannel penetrate into the regions facing radially away from the flowchannel, to the heat shield 3, and the situation is likewise preventedwhere cooling air L fed in on the stator side may pass throughcorresponding leakage points into the flow channel. As already explainedinitially, the clearance 11 provided in the recess 10 serves for athermally induced material expansion along the heat shield 3, with theresult that the joining contour 8, together with the seal 12 provided init, is displaced into a position on the right, evident in theillustration. When, by contrast, the gas turbine stage is shut down andthe individual components cool down, the joining contour 8, togetherwith the seal 12 provided in it, returns to the original initialposition. It is obvious that, due to the thermally induced relativemovements between the reception contour 8 and the surface region 17, theseal 12 is subject to material abrasion phenomena which, when a maximumpermissible tolerance limit is exceeded, lead to a wear- inducedreduction in the sealing function of the seal, so that cooling air L canescape through the intermediate gaps which occur or are already presentbetween the joining contour 8 and reception contour 10. This not onlyleads to a considerable loss of cooling air, with the result that thecooling action is drastically reduced, but there is also the risk thathot gases may also enter regions which face away from the flow channelwith respect to the heat shield 3. In addition, usually seals are usedwhich consist of a fabric material which may be thinned out underexcessive mechanical frictional stress, with the result that the sealingaction of the seal decreases with increasing operating time.

SUMMARY

The object on which the invention is based is to provide a heat shieldfor the location separation of a flow channel within a turbine engine,in particular a gas turbine plant, with respect to a stator housingradially surrounding the flow channel, with two axially opposite joiningcontours which can each be brought into engagement with two componentswhich are axially adjacent along the flow channel and which each providea complementary reception contour for the joining contours, of whichreception contours at least one reception contour has an axialclearance, along which the joining contour joined in it is mountedaxially displaceably, at least one seal being provided between theaxially displaceable joining contour and the reception contour, in sucha way that the seal is to reduce or considerably lower abrasion causedby relative movements between the joining contour and the receptioncontour which are brought about by the thermally induced materialexpansions and shrinkages.

In particular, it is appropriate to take measures which considerablyreduce the wear of the seals, although the measures to be taken here areto be executable as simply as possible in structural terms. Finally, itis appropriate decisively to prolong the maintenance cycles of themaintenance-subject components on the heat shield, thus with particularregard to the seals, and to improve their operating reliability.

The present invention is a heat shield arrangement for local separationof a flow channel within a turbine engine, with respect to a statorhousing radially surrounding the flow channel. The heat shield includestwo axially opposite joining contours which are each engageable with twocomponents which are axially adjacent along the flow channel. Eachprovides a complementary reception contour for the joining contours. Atleast one of the reception contours has an axial clearance, in which theassociated joining contour is axially displaceably mounted. At least oneseal is provided between the axially displaceable joining contour andthe reception contour. The seal is mounted movably within the receptioncontour or the joining contour in such a way that the seal isdeflectable against a surface region of the reception contour or of thejoining contour.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is described below by way of example, without anyrestriction of the general idea of the invention, by means of exemplaryembodiments, with reference to the drawings in which:

FIG. 1 a shows a diagrammatic partial longitudinal sectionalillustration through a joining region between a heat shield and anaxially adjacent guide vane,

FIG. 1 b shows a perspective illustration of the sealing element with aspring element in a vertical projection above a recess within thejoining contour,

FIGS. 2 a, b show a partial longitudinal sectional illustration througha heat shield with axially adjacent guide vanes and an illustration of adetail relating to this according to the prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Introduction to theEmbodiments

According to the solution, a heat shield is designed, according to thefeatures of the preamble of claim 1, in such a way that the seal ismounted movably within the reception contour or the joining contour insuch a way that the seal can be deflected by the action of force againsta surface region of the reception contour or of the joining contour.

According to the present invention, the seal, which preferably consistsof a metallic material, preferably of an incompressible material, isintroduced within a recess along the reception contour or joiningcontour, but is additionally deflected or pressed against a surfaceregion of the reception contour or joining contour by the action offorce, preferably by the action of spring force. The followingconsiderations provide for integrating the seal into the joining contourof the heat shield, so that the seal is pressed by the action of springforce against a surface region of the reception contour. It is likewisealso possible, however, to integrate the seal in a corresponding recessprovided within the reception contour, so that the seal is pressedagainst a surface region of the joining contour. The choice of mountingof the seal will be governed by the respective structural conditions ofthe joining connection between the heat shield and the axially followingcomponent of the gas turbine plant. Without any restriction to thegeneral idea of the invention, the seal design according to theinvention will be described below as an integral constituent of thejoining contour of the heat shield. In this regard, reference is made tothe exemplary embodiment described in the Figures.

DETAILED DESCRIPTION

FIG. 1 a shows a partial view of a longitudinal section through a heatshield 103 in the region of the joining contour 108 which issues into acorresponding groove-shaped reception contour 110 of an axially adjacentroot of a guide vane 101′. The axial depth of the reception contour 110is dimensioned, in such a way that, in the case of a thermally inducedmaterial expansion of the heat shield 103, the joining contour 108 ismounted slideably along the axially oriented clearance 111. The joiningcontour 108 consequently executes a translational movement indicated bythe direction of the arrow E′. In the exemplary embodiment illustratedin FIG. 1 a, the joining contour 108 has a radially outer joining face116 in which a groove-shaped recess 114 is incorporated. The depth ofthe groove-shaped recess 114, measured from the joining face 116,corresponds at least to the maximum radial extent of the seal 112, theshape of which is adapted to the inner contour of the groove-shapedrecess 114, so that the seal 112 can be pushed completely into therecess 114. Furthermore, within the groove-shaped recess 114, a springelement 118 is provided which is introduced between the groove bottom ofthe recess 114 and the seal 112, so that the spring element 118 candrive the seal 112 radially upward. For a supplementary overview of thedesign of the seal 112, of the spring element 118 and of thegroove-shaped recess 114 within the joining contour 108, reference ismade to the perspective illustration according to FIG. 1 b, which is tobe considered below together with FIG. 1 a.

The seal 112 is designed in the form of a rod in the way illustrated inperspective in FIG. 1 b and is preferably manufactured from anincompressible metallic material which has essentially no abrasionproperties. The seal 112 has centrally a rectangularly formed protrusion119 which engages into a correspondingly rectangularly formed recess 120in the inserted state within the groove-shaped recess 114. The seal 112is positively guided linearly in the radial direction by the protrusion119, so that the seal 112 is prevented from slipping out of place in thecircumferential direction along the groove-shaped recess 114. Betweenthe seal 112 and the bottom of the groove-shaped recess 114, a springelement 118 of curved form is introduced, which can press the seal 112radially upward by the action of spring force. In order to prevent thespring element 118 from slipping out of place in the circumferentialdirection along the groove-shaped recess 114, the curved spring elementportion 118′ facing the groove bottom issues into a corresponding recessdisposed in the groove bottom.

The boundary wall 121, axially opposite the rectangularly formed recess120, within the groove-shaped recess 114 is manufactured from a sealingmaterial and can thereby come into fluidtight contact with the seal 112.

FIG. 1 a illustrates the inserted state of the joining contour 108within the reception contour 110, it being evident in the longitudinalsectional illustration illustrated that the spring element 118 pressesthe seal 112 radially outward against a surface region 117 of thereception contour 110 and therefore presses the heat shield 103 in afluidtight manner against the reception contour 110 within the root ofthe guide vane 101′. In order to ensure that the seal 112 is pressed bythe action of force both against the surface region 117 and at the rearagainst the boundary wall 121, the radially lower side edge of the seal112 is of obliquely inclined design, so that the spring element 118 canalso press the seal 112 axially against the rear boundary face 121 in afluidtight manner.

In order to improve the sealing action of the seal 112 against thesurface region 117 of the reception contour 110, the side edge of theseal which faces the surface region 117 is designed to be contour-truewith respect to the surface region 117.

Although the sealing system designed according to the present inventioncannot avoid the axial longitudinal movements of the heat shield 103caused by the thermal material expansion or shrinkage, nevertheless,with a suitable choice of the seal material, material abrasion becomesentirely irrelevant, especially since the seal 112 is selected from anincompressible wear-free preferably metallic material which ensuresfluidtight sealing on account of the pressure caused by the action ofspring force.

It is likewise conceivable to provide the seal arrangement acted upon byspring force alternatively in the region of the reception contour 110,such as, for example, in the region of the boundary face, instead ofwithin the joining contour 108 in the way indicated in FIGS. 1 a and 1b.

Furthermore, the cooling air L′ flowing in under high pressure can exerta high pressure force on the axially directed face 123 of the protrusion119 within the cooling volume V′ enclosed by the heat shield 103, sothat, in addition to the spring force component, the seal is pressed inthe axial direction against the boundary side 121 consisting of sealingmaterial.

In addition to the actual embodiment of the spring element 118 which isillustrated in FIGS. 1 a and 1 b, further spring element designs mayalso be envisaged, such as, for example, a multiplicity of individualhelical spring elements helically shaped or coiled spring elements andsuitably shaped flat springs.

Moreover, for the sake of completeness, it is pointed out that the heatshield illustrated in FIGS. 1 a and 1 b delimits in a ring-like multiplearrangement the entire circumferential region between two guide vanerows arranged adjacently to one another. For this purpose, two heatshields arranged adjacently to one another in the circumferentialdirection are in engagement via a common strip band seal 124, by meansof which a possible loss of cooling air along two heat shieldscontiguous to one another in the circumferential direction can beavoided.

The sealing arrangement according to the invention thus affords thefollowing advantages:

The leaktightness of the cooling air volume which is separated from theflow channel by the heat shield is considerably improved by virtue ofthe wear-free seal, especially since the sealing action is ensured,despite thermal expansion and shrinkage phenomena, by the seal beingpressed by the action of spring force against the respective surfaceregion lying opposite the seal.

Regardless of predetermined tolerance dimensions in terms of the designof the reception contour or of the joining contour, the pressing of theseal caused by spring force ensures at any time a sealing of the joiningregion with respect to its radially upper and lower boundary faces,especially since the radially upper seal 112, by virtue of thecounterforce exerted on the joining region, can also press the radiallylower boundary face of the joining region against the boundary face ofthe reception contour 110 in a fluidtight manner. Should the seal beprovided in the region of the boundary face, the same appliesaccordingly.

Due to the pressing action of the seal 112 against the surface region116 of the reception contour 110 by the action of spring force, thespring element 118, because of its inherent elasticity, contributes to acertain capacity for the absorption of shocks or vibrations, so thatmechanical vibrations occurring within the joining region can beabsorbed by the spring element 118 and therefore do not subject thejoining region to excessively high mechanical stress.

LIST OF REFERENCE SYMBOLS 1, 1', 101' Guide vane 2 Rotating blade 3, 103Heat shield 4 Intermediate gap 5 Ribs 6 Abrasion elements 7, 8, 108Joining contour 9, 10, 110 Reception contour 11, 111 Axial clearance 12,13, 112 Seal 114 Groove-shaped recess 15 N/A 16, 116 Joining face 17,117 Surface region 118 Spring element 118' Part region of the springelement 119 Protrusion 120 Recess 121 Boundary face 123 Radial side faceof the protrusion 124 Strip band seal

1. A heat shield arrangement for local separation of a flow channelwithin a turbine engine, with respect to a stator housing radiallysurrounding the flow channel, the heat shield comprising two axiallyopposite joining contours which are each engageable with two componentswhich are axially adjacent along the flow channel and which each providea complementary reception contour for the joining contours, at least oneof the reception contours has an axial clearance, in which theassociated joining contour is axially displaceably mounted, at least oneseal being provided between the axially displaceable joining contour andthe reception contour, the seal is mounted movably within the receptioncontour or the joining contour in such a way that the seal is deflectedagainst a surface region of at least one of the reception contour or ofthe joining contour, the joining contour including a joining face inwhich is introduced for the seal a recess out of which the seal isdeflectable so as to project partially beyond the joining face into agap defined between the reception contour surface region and the joiningface.
 2. The heat shield as claimed in claim 1, wherein at least one ofthe reception contour or the joining contour has a joining face in whichis introduced for the seal a recess out of which the seal is deflectableso as to project partially beyond the joining face.
 3. The heat shieldas claimed in claim 2, wherein at least one spring element, thatdeflects the seal by the action of spring force, is provided in therecess.
 4. The heat shield as claimed in claim 3, wherein the at leastone spring element is designed as a curved bar spring and is held in thelongitudinal direction with respect to the recess.
 5. The heat shield asclaimed in claim 3, wherein the recess has a radially oriented boundaryface which consists of a sealing material, the seal has a radially upperside edge which is adapted to the surface region against which the sealcan be pressed, and the seal has a radially lower sloped side edge,against which the spring element presses, and an inclination of theslope is selected in such a way that the seal can be pressed bothagainst the surface region and against the boundary face consisting ofthe sealing material.
 6. The heat shield as claimed in claim 3, whereinthe seal is comprised of a metallic material.
 7. The heat shield asclaimed in claim 3, wherein the seal is an incompressible solid body. 8.The heat shield as claimed in claim 3, wherein the seal is bar-shapedand has a local protrusion along its extent, and the joining contourcomprises a recess, which is adapted to the protrusion and along whichthe protrusion is guided in the radial direction, is provided in therecess.
 9. The heat shield as claimed in claim 2, wherein the seal isbar-shaped and has a local protrusion along its extent, and the joiningcontour comprises a recess, which is adapted to the protrusion and alongwhich the protrusion is guided in the radial direction, is provided inthe recess.
 10. The heat shield as claimed in claim 2, wherein the sealdeflectable by spring force against the surface region of at least oneof the reception contour or of the joining contour.
 11. The heat shieldas claimed in claim 2, wherein the seal is comprised of a metallicmaterial.
 12. The heat shield as claimed in claim 2, wherein the seal isan incompressible solid body.
 13. The heat shield as claimed in claim 1,wherein the seal deflectable by spring force against the surface regionof at least one of the reception contour or of the joining contour. 14.The heat shield as claimed in claim 13, wherein at least one springelement, that deflects the seal by the action of spring force, isprovided in the recess.
 15. The heat shield as claimed in claim 13,wherein the seal is comprised of a metallic material.
 16. The heatshield as claimed in claim 13, wherein the seal is an incompressiblesolid body.
 17. The heat shield as claimed in claim 13, wherein the sealis bar-shaped and has a local protrusion along its extent, and thejoining contour comprises a recess, which is adapted to the protrusionand along which the protrusion is guided in the radial direction, isprovided in the recess.
 18. The heat shield as claimed in claim 1,wherein the seal is comprised of a metallic material.
 19. The heatshield as claimed in claim 18, wherein the seal is an incompressiblesolid body.
 20. The heat shield as claimed in claim 1, wherein the sealis an incompressible solid body.